A new client has a serious corruption error.
During a hot backup (not RMAN) Thursday morning it was discovered that a
datafile was corrupted on the disk. When the database is started up, the
following error occurs:

When dbverify is run against this file, every block
is indicated as corrupt, which isn't surprising.

We have a copy of the datafile from
Wednesday's hot backup, but they don't have the archivelogs necessary to sync
this datafile with the rest of the database. And we don't have the
other datafiles from Wednesday's backup, so we can't just go back to the state
the database was in then.

Any ideas on what they can do? I can't think
of anything (other than going back to an export they have from 6 months ago,
which seems to be the only historical backup they have).